As processes for producing cyclic alcohols by hydration of cyclic olefins, processes of indirect or direct hydration reaction using mineral acids, particularly sulfuric acid, have conventionally been known. As other homogeneous catalysts for the reaction, aromatic sulfonic acids as described in Japanese Patent Publication No. 8104/68 and Japanese Patent Publication No. 16123/68, heteropolyacids such as phosphotungstic acid or phosphomolybdic acid as described in Japanese Patent Application (OPI) No. 9746/78 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), etc., have also been proposed.
However, use of these homogeneous catalysts involves serious problems due to the corrosiveness of the catalysts with respect to materials used for reactors or the like and deterioration of the catalysts. In addition, since the reaction product produced with the aid of these catalysts exists mostly in an aqueous phase, separation and recovery of the product from the aqueous phase requires complicated procedures and much energy.
As a process for overcoming these defects, it has been proposed to use solid catalysts, for example, ion exchange resins as described in Japanese Patent Publication Nos. 15619/63 and 26656/69.
However, such ion exchange resins have the problem of deterioration of catalyst activity due to reduction in size of the resin by mechanical disintegration and due to insufficient heat resistance of the resin, thus being unable to provide stable catalyst activity over a long period of time.
Further as a process of using a solid catalyst, it has been proposed to use crystalline aluminosilicates. Crystalline aluminosilicates are insoluble in water and have excellent mechanical strength and heat resistance, thus being expected to be utilized as industrial catalysts. Thus, Japanese Patent Publication No. 45323/72 proposes a process for producing alcohols by hydration of olefins using dealkalized mordenite, clinoptilolite, or faujasite type zeolite as a catalyst.
Japanese Patent Publication No. 45323/72 describes in Example 4 an example of using cyclohexene as the cyclic olefin. According to the description of Example 4, the reaction is conducted in an autoclave at a reaction temperature of from 200.degree. to 210.degree. C. for a reaction time of from 10 to 15 hours to obtain a conversion of water to cyclohexanol of as low as 0.05 to 0.06%. Calculation of the conversion of cyclohexene to cyclohexanol based on the above description gives a conversion of 0.07 to 0.08% and, in turn, calculation in the same manner of the concentration of cyclohexanol in water based on this conversion gives a concentration of about 0.3%. No description appears therein as to selectivity of reacted cyclohexene to cyclohexanol and production of by-products. With the hydration reaction of propylene or 1-butene also described in the same Example, conversions of the straight chain olefins to corresponding alcohols are as high as 10 to 20% and 4 to 7%, respectively (calculated based on the conversions of water as in the above-described case, with the concentrations of the resulting alcohols in water, calculated based on these conversions, being 9 to 20% and 4 to 6%, respectively). In contrast, the Example shows that hydration reaction of cyclohexene to cyclohexanol is not practical due to too low conversion to cyclohexanol.
U.S. Pat. No. 4,214,107 describes examples of gaseous phase catalytic hydration reaction of straight chain olefins such as ethylene, propylene, etc., using HZSM-5 (proton-exchanged ZSM-5 made by Mobil Oil Corporation). However, no descriptions are found therein with respect to cycloolefins.
U.S. Pat. No. 4,324,940 proposes a process of selectively reacting smaller olefins by effecting acid-catalyzed reactions of a mixed stream composed of smaller olefins and larger olefins using a crystalline zeolite. According to the description in this patent, the acid-catalyzed reactions include hydration reactions, and the olefins include cycloolefins. However, no examples thereof are given therein. In addition, it is described therein, from col. 6, line 4 up to col. 7, line 3, that zeolites of larger crystal size are more effective.
Japanese Patent Application (OPI) No. 70828/82 proposes a process for producing alcohols by hydration of olefins using specific crystalline aluminosilicates of Mobil Oil Corporation, such as ZSM-5 or ZSM-21. However, no examples of reacting cyclic olefins as olefins are given therein. Example 1 shows a reaction of propylene as a straight chain olefin, wherein the reaction is conducted at 200.degree. C. for 2 hours followed by an after-treatment of removing unreacted propylene and the catalyst to obtain an aqueous filtrate containing 8.7 wt% isopropanol. On the other hand, Example 3 shows a reaction of 1-butene, wherein the reaction is conducted at 160.degree. C. for 2 hours followed by the same after-treatment as described above to obtain an aqueous filtrate containing as low as 1.2 wt% sec-butyl alcohol.
Japanese Patent Application (OPI) No. 124723/83 proposes a process for producing alcohols by hydration of olefins using as a catalyst a partly dealuminated zeolite whose exchangeable ions have been wholly or partly exchanged with protons, an ion of an element of the group II or VIII of the Periodic Table, or of an earth metal element or rare earth element. However, reaction examples on cyclic olefins are not described therein. As examples of straight chain olefins, Example 1 shows a reaction of n-butylene, wherein the reaction is conducted at 170.degree. C. for 2 hours followed by removing unreacted n-butylene and the catalyst to obtain a filtrate containing at most 3.4 wt% sec-butyl alcohol.
In view of the difference in reactivity between straight chain olefins and cycloolefins shown in Japanese Patent Application (OPI) No. 4532/72 and the difference in reactivity between straight chain olefins shown in the Examples therein, extremely low reactivity is expected in the synthesis of cyclic alcohols from cyclic olefins using the catalysts specified by the aforesaid U.S. Pat. Nos. 4,214,107 and 4,324,940 and Japanese Patent Application (OPI) Nos. 70828/82 and 124723/83. In addition, there are no information therein on side reactions or other problems that occur.
Where the conversion of cyclic olefin to cyclic alcohol is low, there also arises a problem with respect to recovery of the cyclic alcohol produced. That is, in contrast to alcohols derived from straight chain olefins, all cyclic alcohols have higher boiling points than the other reactant, water, and hence water must be first removed from the system, followed by distillation or the like to separate and recover the cyclic alcohol. Thus, the recovery requires much heat, which leads to seriously increased costs and brings about a problem with respect to practical utility. Further, with cyclic alcohols forming azeotropic compositions with water, the boiling points of the azeotropic compositions are close to that of water, which similarly requires, in view of the large proportion of water in the compositions, seriously increased costs for separation and recovery of cyclic alcohols.